Coded data generation or conversion – Analog to or from digital conversion – Analog to digital conversion
Patent
1993-04-30
1994-10-18
Hoff, Marc S.
Coded data generation or conversion
Analog to or from digital conversion
Analog to digital conversion
341155, H03M 112
Patent
active
053572513
ABSTRACT:
An electronic filter for filtering an electrical signal. Signal processing circuitry therein includes a logarithmic filter having a series of filter stages with inputs and outputs in cascade and respective circuits associated with the filter stages for storing electrical representations of filter parameters. The filter stages include circuits for respectively adding the electrical representations of the filter parameters to the electrical signal to be filtered thereby producing a set of filter sum signals. At least one of the filter stages includes circuitry for producing a filter signal in substantially logarithmic form at its output by combining a filter sum signal for that filter stage with a signal from an output of another filter stage. The signal processing circuitry produces an intermediate output signal, and a multiplexer connected to the signal processing circuit multiplexes the intermediate output signal with the electrical signal to be filtered so that the logarithmic filter operates as both a logarithmic prefilter and a logarithmic postfilter. Other electronic filters, signal conversion apparatus, electroacoustic systems, hearing aids and methods are also disclosed.
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Engebretson A. Maynard
Engel George L.
Morley, Jr. Robert E.
Sullivan Thomas J.
Central Institute for the Deaf
Hoff Marc S.
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